Thermostat.



PATENT OFFICE.

1 HARRY G. GEISSINGER, OF NEW YORK, N. Y.

TEERMOBTAT.

Specification of Letters Patent.

Patented Sept. 10, 1907.

Application filed July 1B 1906. Serial No. 326,442-

J'o all whom it may concern:

Be it known that l, HARRY G. Gmssmonn, a citizen of the United'States,and residing on the St. Paul steamer of the American line, the saidAmerican line having an office in the city of New York, State of New-York, have invented new and useful Improvements in Thermostats, of whichthe following -is a specification. g

My invention relates to electric thermostats and its. object is toprovide a thermostat thatpossesses novel features which enables it tocontrol and regulate temperature even though it may be subjected tooscillations and vibrations such as would occur on board ships or movingtrains.

The invention consists in locating an electro-magnet in the vicinity ofa thermal bar, one of the poles of the elcctro-magnet operating as acontact whereby a controlling circuit is closed through the saidcontact. The invention also consists in utilizing the remaining pole ofthe magnet to control the motion of the bar relative to the change oftemperature. 4

The invention consists in other features disclosed in the followingdescription, illustrated in the drawings and set forth in the claims.

Referring to the drawings Figure 1 is an elevation of a thermostatembodying the principles of my invention. Fig. 2 is an end view and Fig.3 is a plan of my apparatus. Fig. 4 is a diagrammatic sketch showing inan exaggerated manner the action of the thermostat bar under theinfluence of changes of temperature.

In the drawings, 1 is a (I-shaped compound bar formed of dissimilarmetals 2 and 3, for instance, brass and iron. The dissimilar metals arelocated on opposite sides of the two legs of the U bar. The bar may beformed by cutting a U-shaped piece from one of the metals and thenattaching strips of the other metal on the opposite side of the U pieceas shown in the drawing. The bar 1 is secured at 4 to the framework 15of the apparatus and is insulated therefrom by a gasket or other device5. The other end 16 of the U-bar is allowed to move freely ashereinafter described. The free end 16 of the U-bar is located inproximity to an adjustable contact point 6 and is adapted to movetowards or away from the said adjustable contact point 6 as the U-bar isinfluenced by changes of temperature. The free end 16 is provided with acontact 17 which is adapted to make contact with the contact 6.

The contact point 6 is mounted on the end of or forms a part of an ironscrew 7 which is located at one end of and movable in a bar 8 formingthe core of a magnet coil 9. The bar 8 extends through the coil 9 and isprovided at its other end with an adjustable iron screw 1]. The ends ofthe screws 6 and 10 form, therefore, two adjustable poles of the magnet9. 12 is a wire leading to one end of the magnet coil 9. 13 is a wireconnecting the coil 9 with the contact point 6 through the screw 7 andbar 8. 14 is another wire leading from the fixed end of the thermostatbar and completes the circuit when the free end of the bar touches thecontact point 6. The apparatus may be suspended by means of these wiresor by other separate flexible means and the arrangement of the wires maybe modified without changing the substance of the invention. I

Having thus given a general description of my improved electricthermostat, I will now explain its operation. Assuming now that underthe influence of temperature the free end of the U-bar is deflectedowing to the unequal expansion of. the dissimilar metals 2 and 3 andthat this deflection carries the free end of the bar towards the contactpoint (5 until it touches it. This contact'if closed for any appreciablelength of time will allow the current which is assumed to exist in thewires to pass through the coil 9. This will immediately create amagnetic flux which will pass from the poles 6 and 10 through themagnetic ele- -ment of the compound bar 1 between these points.

The pole 10 is located near the middle of the free leg of the U-bar forthe purpose hereinafter described and is adjusted so that the bar 1never touches it. The resultis that bothpoles 6 and 10 attract the bar 1and bind it against the contact point 6 while the magnetic fluxemanating from the pole 10, passing, as it does, through the layer ofnon-magnetic material 2, creates eddy currents which form poles in thevibrating bar of similar or opposite character to the poles of the mag.-net 9 and in their vicinity as the bar in its vibration is towards oraway from the poles of the magnet which tends to restrain the vibrationthereof, after the well known principle used in voltmeters,galvanometers and other similar instruments. On the assumption that theregulating circuit has been closed by the thermostat due to a fall oftemperature and that a source of heat has been turned on by this action,itwill be clear that with an increase of the surrounding temperature,the bar 1 will tend to pull away from the contact point 6, but cannot doso until the tension overcomes the magnetic attraction of the poles 6and 10. When'thc break occurs, the bar 1 springs away a certain amountand the magnetism disappears. Therefore, it happens that the thermostatlags behind the rising temperature a certain definite amount which mustbe regulated to meet the conditions under which the thermostat isexpected to work. The rcgulationof this lag or difference between theworking temperature of the regulator and that of the surrounding medium,is one of the most valuable features of my invention. It is accomplishedby adjusting the screw 11 so that the air gap is either decreased orincreased as the case may require. For instance,v if it is desired toincrease the lag, the air gap is decreased, that is to say, the magneticaction of the pole 10 is rendered more powerful by turning the screw 11so that it approaches the bar 1. If it is desired to decrease this lag,the operation is reversed. In either case, the adjustment is permanentand is totally independent oithe adjustment of the screw? to the workingtemperature, as will be readily seen by reference to the diagram shownin Fig. 4. It will be observed that the free portions of the thermostatbar curve in opposite directions under the influence of a 10 change oftemperature, on account of the similar metals -being on opposite sidesof the two sections of the U-bar. This action is illustrated in anexaggerated form in the diagram, but it serves to show that the free legof the U-bar crosses the original plane of the whole bar at a pointhalfway, or very nearly so, between the extremities of the bar.Therefore, inasmuch as the pole 10 is located at this middle point, therequired adjustment of the magnetic action of the coil 9 is not affectedby the adjustment of the screw 7 for working temperature, as will bereadily understood.

It is well known that a thermostat bar must be thin and haveconsiderable length in order to produce any appreciable divergence underthe influence of changes of temperature. Such a. bar is necessarily veryelastic and is inclined to vibrate whether it be supported at the fixedend only or whether it be supported at both of these conditions cause arapid opening and closing of the circuit which is very destructive toelectric switches or other apparatus controlled by the thermostat.

It should be noted that, on account of the U-shape of my compound bar,the vibrations are naturally more rapid than in a straight bar ofequivalent length, also that the vibrations of theU-bar move through amuch smaller arc. Therefore, the time of the initial vibrating contactsis much shorter and, consequently, the apparatus is not afiected by theweak magnetism developed by such short contacts. The magnetism developedbecomes strong enough to hold the bar 1 against the point 6,'therebyclosing the circuit, only when the action of the temperature hassufiiciently deflected the bar so as to produce a prolonged contact.After this contact is made, the dampening action of the pole 10 furtherrestrains the local vibrations of the com pound bar, thereby renderingthe action of the apparatus very positive. Thus, the device or apparatusto be regulated is not subject to the action of my thermostat until therequired temperature has been reached It should also be noted that onaccount of the U-shape of my thermostat bar, I am able to use acomparatively long length of bar within a small space, which, of course,makes the apparatus very sensitive while very compact. -Therefore,.being in position to adjust the lag of the apparatus and to overcome thedeleterious effects of false contacts by the dampening action of thepole 10 on the vibrations of the bar, it is possible to adjust mythermostat so that the effect of vibrations due to the natural movementsof steamships or railroad trains, may be nullified entirely. Moreover,by reason of the existence of the lag, the working temperature liesbetween the temperature which produces contact and that which causes thebreaking of the circuit, and the heat generating apparatus is turned onand off at much longer intervals than would be the (use with thermostatshavingstraight bars.' This results in the saving of much wear and tearin valves and switches operated by my thermostat, as well as power. Itis found by experience that a lag of one-half degree of temperaturecorresponds to a magnetic action perfectly able to nullifyall thevibrations due to the motion of a steamship in a heavy sea.

The invention may be modified in its details by those skilled in the artwithout departing from the spirit of the invention. Y

Having thus given a description of my invention, what I claim as new anddesire to. cover by Letters Patent is as follows:

1. A thermal bar for thermostats, comprising a substuntlally U-shapcdmetallic plate, both legs of said bar occupying substantially the sameplane, said bar having a plate of a dissimilarmetal secured to a portiononly of one face thereof. 4

2. A thermal bar for thermostats, comprising a substantially II-shapedmetallic plate, both legs of said bar 4. In a thermostat, incombination, a supporting frame,

an electromagnet having two adjustable pole pieces, and a fiat recurvedthermal bar so mounted on said frame as to make electrical contact withone of said pole pieces, the other pole piece being located opposite apoint intermediate the extremities f said thermal bar'.

5. In a thermos it, the combination of a supporting frame, anelectromagnet mounted on said frame and having two adjustable poles, oneof the said poles forming a contact polnt, a U-shaped thermal bar, bothof the'legs of which lie in substantially the same plane, one leg of thesaid bar being secured to said frame and the other leg thereof free tomake contact with one of the poles of said magnet and move in thevicinity of the other pole thereof.

6. In a thermostat the combination of an electromagnet having twoadjustable poles, one of said poles being electrically connected withsaid eleetromagnet, a U-shaped thermal bur, both of the legs of--whichoccupy substantially the same plane, said bar having one extremity fixedand the other so located as to close the circuit through the said poleof the said electromagnet and having the intermediate portion of thefree leg of the ll-shaped bar in -the magnetic field of the other of.the said poles.

7. In a thermostat, in combination, a supporting frame, an electromagnetmounted thereon, a U-shaped thermal bar, both legs of which lie insubstantially the same plane. one leg of said bar being secured to saidframe and the free extremity of the other leg forming one terminal of anelectric circuit, one pole of the electromagnet forming the otherterminal of said circuit, un electromagnet-coll located in said circuit,and the other pole of said magnet being located near an intermediatepart of said thermal bar to damp its vibrations when said circuit isclosed.

8. An electric thermostat comprising an electric circuit, a thermal barcarrying one terminal of said circuit, an electromagnet having asubstantially straight core, one pole of which core carries the otherterminal of said circuit, an energizing coil for said magnet alsolocated in said circuit, the other pole of said magnet-core beinglocated near an intermediate part of said thermal bar to damp itsvibrations when said circuit is closed.

9. In a thermostat, the combination of a supporting frame, anelectromagnet, a II-shaped thermal bar having both its legs insubstantially the same plane, the end of one leg of said bar beingsecured to said frame near one pole of said magnet and the other legpassing near the other pole thereof and carrying at its free end aContact point for closing iiil' circuit of said eleciromagnct byconiarliug with the first mentioned pole of said magnet.

ii). in a thermostat, the combination of an electromagnot having twopoles. and a thermal bur closing a circuit through one pole of the saidmagnet, but never touching the other pole. the said poles being locatedon one side of the said bar and arranged to act directly thereon.

11. In a thermostat, the combination of an electromagnet having twoadjustable poles, one of the said poles forming a contact point, a(I-shaped thermal bar making contact with one of the said poles andmoving in the vicinity oi. the other of the said poles.

12. In a thermostat, the combination of an electromagnet having twoadjustable poles, one of the said poles being electrically connectedwith the said electro-magnet a U-shaped thermal bar closing thecircuitthrough the said pole and having the central port-ion of one oi!its limbs in the vicinity of the other or the said poles.

- 13. In a thermostat, in combination, a supporting trame minal of thefree end oi! said thermal-bar carrying a con tact enclosing the circuitof the magnet coil through the pole located nearest the point ofattachment of the thermal bar.

In testimony whereof; I have signed my name to this specification, inthe presence or two subscribing witnesses.

HARRY G. GEISSINGER.

Witnesses J.- It. Wmunmoms, Jsxns BARCLAY.

